While previous diabetes studies showed a higher incidence of the disease among blacks, Latinos and Asians, a new study by the University of Massachusetts Medical School on women older than 50 found that if healthy lifestyles are adopted, there is a decreased difference among races and ethnicities.

The study, which concluded that much of the variability could be attributed to lifestyle factors, was published today in Diabetes Care, a journal of the American Diabetes Association.

“The high rate of diabetes among certain minorities has been well-documented, but few studies have looked at that disparity in relation to different lifestyle factors in aggregate to estimate the proportion of diabetes that might be avoided by adopting a pattern of low-risk behaviors,” said Dr. Yunsheng Ma, primary investigator of the study and an associate professor at UMass. “Our work shows that among numerous race and ethnicities, the women with both high body mass index and low levels of physical activity are far more likely to develop diabetes.”

He said healthier diets and physical activity significantly lower diabetes risk for most women.

The study used data from the Women's Health Initiative, a National Institutes of Health program started in 1991.

More than 150,000 post-menopausal women were followed for 10 years, with data collected on race, ethnicity, education, existing diabetes and the development of diabetes, as well as weight, height, waist size, body mass index, smoking, diet and physical activity. At enrollment in the study, diabetes prevalence was highest among blacks, at 12.2 percent, followed by Hispanics, Asians, and whites.

The results showed that black women are two to three times more likely than whites to develop diabetes, while Hispanics and Asians are approximately twice as likely. However, researchers found that diabetes among black women dropped from nearly 24 percent in those considered obese, to 8.8 percent in those who had a healthy weight and exercised.

Across all racial and ethnic groups, women of normal weight and body mass index had a one-third to one-sixth incidence of diabetes, compared to women with a BMI greater than 30 who did not exercise.

One of the more interesting aspects of the study found that Asian women had the highest inherent risk of diabetes, Dr. Ma said, and may need to achieve an even greater weight loss to get the same low risk factor for the disease as non-overweight whites. The reason, he said, may be genetic. Even Asian women with small waists and low BMIs are at higher risk.

“Although their dietary quality is higher, if they eat like whites, their risk of diabetes would be increased,” he said.

Researchers found that blacks and Hispanics may be more sensitive to lifestyle modifications and weight loss, especially if education and intervention are incorporated.

A study in Lawrence last year, in collaboration with UMass, used “telenovelas” — popular Spanish-language soap operas — with story lines incorporating healthy food choices and situations to get the point across.

The study published today, supported by the National Institute of Diabetes and Digestive and Kidney Diseases, found that if Hispanics achieved the same education level as whites, their risk of diabetes would decrease by 14 percent.

However, Dr. Ma, an epidemiologist, said access to costly healthy foods and exercise facilities is a barrier, although educational interventions — such as the one in Lawrence — have been successful.

“In a separate study, we also found grocery stores in poor neighborhoods have less fruits and vegetables, and gyms. Therefore, there are two issues here: the cost of healthy foods or gym memberships, and their availability,” he said.

Study researchers acknowledged some limitations in their data.

The Women's Health Initiative participants are not a population-based random sample, and ethnic groups other than whites are under represented. Also, only self-reported cases of diabetes were ascertained, so its incidence could be underestimated. But those limitations are balanced, researchers concluded, because the study represented a racially diverse sample of with detailed information on diabetes risk factors.